Burglar-alarm for door-knobs.



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WILLIAM S. HURST, OF LOS ANGELES, CALIFORNIA.

BURGLAR-ALARM FOR DOOR-KNOBS.

Application filed December 3, 1906. Serial No. 346,189.

Specification of Letters Patent.

Patented Aug. 18, 1908.

To all whom it may concern:

Be it known that 1, WILLIAM S. HURsT, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles, State of California, have invented a new and useful Burglar-Alarm for Door-Knobs, of which the following is a specification.

The main object of this invention is to provide a device which is readily applicable to the knobs of doors for giving immediate notification if the door knob is turned. Such a device is useful in houses, stores, hotels, etc.

A further object of the invention is to provide a device of this character of compact form which can be readily attached to or slipped off of a door knob, and is therefore adapted to be carried by any person, for example in traveling, and can be applied to the door knob in a hotel or elsewhere as the occasion may require, or can be conveniently applied to a house or store door only in the night time and removed in the day time.

In the accom anying drawings :-Figure 1 is a front elevation of the device showing the device attached to and suspended in the door knob in vertical inoperative position. Fig. 2 is a similar view of the device showing the device in operative position. Fig. 3 is a side elevation of the door knob showing the device attached thereto partly in section. Fig. 4 is a detail elevation of the detent and catch devices therefor in operative position.

The device comprises an alarm bell 1 of any suitable or usual construction having an operating or winding handle 2 and a controlling trigger or detent 3, which when pushed in sets the alarm or holds it from running down.

This detent is shown as a shouldered sliding detent, being pushed outwardly by a spring 4 and being held in looking or inward position by a manually operated catch 5 ada ted to be engaged with or released from'sai shoul- The body member or back 7 of the bell is formed with an extension 8 to' which is pivoted at 9 a hanger member 10 formed as a substantially triangular plate having a flange 11 on its base extendin transversely thereto and preferably rounded in concave form as a portion of a sphere to fit under a door knob. A rubber or other elastic band 13 is fastened by suitable means, such as staples 14 to this flange and a clamp member 15 is also referably provided at the opposite portion 0 said band facing inwardly toward the said flange member and oppositely concaved so that the two members 11, 15 are adapted to embrace the door knob, indicated at 16, between them and to tightly grip the same by virtue of the elasticity of the band. Said band is in the form of a loop adapted to extend around the entire circumference of a door knob. The hanger member 10 extends downwardly beyond its pivotal connection 9 to the alarm body extension 8 and is provided at its lower end or apex with a portion adapted to engage the detent 3 to hold the same in inward position. To diminish the friction, this portion of the hanger member is referably provided with an anti-friction rol or 18 which rolls on a flange projection 19 of the detent 3.

The deviceis used as follows :The alarm bell having been Wound by means of its handle 2, is held in that condition by pushing in the detent 3 and locking said detent by the catch 5. The device is then hung on a door knob by slipping the band 13 over the knob and allowing the clamp members 11, 15 to engage with the top and bottom of the knob in such manner that the device hangs vertically, the detent 3 and members 8, 10 as well as the center of gravity of the alarm bell being in a direct vertical line below the axis of the door knob. The catch 5 is then turned to release it from the detent, allowing the detent to engage and be arrested by the lower end of the hanger member 10, or by the antifriction roller thereon. If now the door knob is turned, for example as shown by the arrow in Fig. 2, the alarm bell, hung on a pivotal support 8 will turn on said pivotal support and the anti-friction roller 18 will roll over the detent 3, allowing said detent to spring outwardly, thereby giving an alarm.

What I claim is 1. In a door knob alarm, a substantially triangular plate having its base provided with a concaved flange, said flange being provided with staples, an elastic band secured by said staples to the flange and adapted to encircle a door knob, an alarm pivotally secured to said plate above said apex and provided with two detents, one of which is spring pressed outwardly to engage with the apex of the plate and hold the alarm mechanism against signaling movement when the alarm is in its normal position, and the other detent is manually operable and adapted to be moved into and out of engagement with the spring pressed detent.

2. In a door knob alarm, a substantially triangular plate adapted to have its base detachably secured to adoorknob, a roller operable to engage said shoulder to render 10 journaled to the apex of said plate, and an the alarm inoperative.

alarm pivotally secured 'to said plate above In testimony whereof, I have hereunto set said ape) and provided with two detents, a my hand at Los Angeles, California this 23rd shoulder upon one of said detents, said shoulday of November 1906 dered detent being bent laterally and spring WILLIAM S. HURST. pressed outwardly to normally engage the a In presence of roller and thereby prevent the alarm from ARTHUR P. KN1GHT,

sounding, the other detent being manually FRANK L. A. GRAHAM. 

